Gas turbine power plant supporting structure



May 29, 1956 B. s. SAVIN, JR

GAS TURBINE POWER PLANT SUPPORTING STRUCTURE Filed March 21, 1950 6Sheets-Sheet 1 May 29, 1956 B. s. SAVIN, JR 2,747,367

GAS TURBINE POWER PLANT SUPPORTING STRUCTURE Filed March 21. 1950 eSheets-Sheet 2 Ina/anion?- fieuueii Savz'u Jr.

May 29, 1956 B. s. SAVIN, JR 2,747,367

GAS TURBINE POWER PLANT SUPPORTING STRUCTURE Fil ed March 21, 1950 6Sheets-Sheet 4 /e 242 [n we 31-207" 2 Ben e22 S. avian Jr.

6 Sheets-Sheet 6 May 29, 1956 B. s. SAVIN, JR

GAS TURBINE POWER PLANT SUPPORTING STRUCTURE Filed March 21, 1950 17732870207 .BQWWCZZ S. S 722324 J E W flziormgf United States Patent2747367 w J V @AsmuRBnwmmwER-mmm:sUProRrmG "STRUCTURE tApplicationMarch-21 1950gSerial No. 150;858

' In multistage, "alliaffiowcompressors, itlhas be en found adyantageousto split the compressor and have one,part '(.gefierai1ly" severalstages) driyenhy one or more turbine sta es withthe remaining compressorstages independently driyen by the remainderof the turbine stagesl re- Isiiltsjgenerally in a constructionin which an, ou ter spoo1pressurescompressor stages connected to and drivenby theiliigh-pressurerstage-orstages of the turbinegsurrounds and-rotates onan-axis concentric to the inner spool or lgw pressure .unit. h The latterconsist-s of the-remainder stages. it A; feature {Ofth iS invention is'the supportof the outer-spool within the supporting "structure toprovide for rotation independentlyof the IOWyPl'CSSHF-Cdlnit. :An-

other feature is the independent support of-each unit fromthesupporting'structure=in =suchIa mannerthat'ieither .unibmaybeseparately mounted and rotated '-withinthe supporting housing as, forexample, in testing-each sepa- =rate unit for balance. .-0ne-featureflof'the' invention is'the drive of :thetp'ro- 21381161- 1system frolnone of the :units leaving ithe-other i f .1

tunitlfree tofiset its own 'speed of rotation. Anotherl featune is anarrangement of a brake for'ih'olding- 'one or the 'ellnits statio'nalfy' while the "I otherts "operating 21s, for

vexamplepwliile'. starting and 'warming up' the 'pbwer l' The brake alsoserves totprevent windmillin'g bf the prb- H V 1 115616!whi'leman'euverirtg on ground or earrieru k twith' a 'dividedtpowerplant o'f this typ g-" it is g -'to start it by CI alikiHg UH1YG116ofthe ufiits with the t'i'therrnnit heltl stationary Jeni ne'erta'ineases, with the 'tother unit-allowed' to rotate freely anderthe irifluence vdfthe fiow of gas *through' the eornpressor and turbine.(A r'feat ur'e of t'his 'ihvehtibn is tne arrangement 1 f ine fistartingilrive for the mute spool (if-high pressure ufiit "independently 'oftheotlter unit. in

Narni mounting a hot ga's' turbine within a surrolindifig mousing, itismeeess' of radially extending supporting pins for the meme ofthecornpressor stages-driven-by the remaining turbinedrawingswhichillustrate anembodim'ent 'oftli'einvefltion.

Fig. 5 is a sectional view of the turbine struEturefIslibstarltially'b'e'tween 'the lines D"and"Ej'ofFig. 1. e

Fig.6 'is a sectional View of a 'detailof th'el c'onjpressbr 'housin'gas'sernbly. 1:. y i

Fig. 7 is a sectional Viewo'f a 'de'tailof the' -cblilpressbrvane'jassembly. g 20. Fig. '"8 is "a sectional, viewsubstantiallyonlline atrigfa;

.ig. '9 is a fragmentary sectional viewer the-turbine mounting. 1 i e lFig.,1"0.is a fragmentary .detailjo' f one ofsthe .w infla ge "covers. gy

Fig. .11 isa fragmentary sectional *view of thebrake .assenibly. t l

The power -plant, as shown, consists of asmultistage, saxial flow:compressor consisting-0f two tseparate seetions, the high-pressuresectionzof:which=is-driven-from therfirst turbine stage and-is mountedto\rotateomtheisamemxis as the rest of the compressorbutindependently:ofr it. l he :low ,pressure compressor .section and the.propeller --are5driyen from the remaining 'turbin'e stages. rReferringfirst torFi'g'. 1, theypropellerlwis mounted -at lthevforward -:end -ofthetpower, plant and maylhavea ducted-i spinner inl e't 'by which air"enters the tcompressor24. il he 'idir flows axially' through thecompressor and thericeeintofflie -Iburnermr co'mbustion t chamber:section 6 fihere tit is heate'dfby burni'ngtuel therein. Gasffromstlrestiumr .nseotion is s'dischargedintozthe turbineifi, fnoinwhieh the fias exha'usts'throughma :thrust' nozzle 510.

Thepropellerisdriven-through:a1 retl11cti0n gear drive,

bestnshown in Fig. '2. .The propellefish'aft 1 2 is journalled "inbearings r14 carried byt plate 16-Isuppo'rted at its oll'ter "edge by :aframe element 1=8' consis'ting='ofi inner and buter s rings zl) "and {22spaced apart'iby' integral vanes 2'4""to vform-an annular in1e't 25 forthe eomp'ressor. "The'propelle'rhaft is journalled at 'its rearwardiendwitliinrhe end b61126 of the first or low ressure compressor seeing 30supported by-a-plat'e32Fwhichengages"atitsiouter e'jd'ge' w ith thein'n'er sleeve'34 of a'pair'of'sleeves 33am! 36 "which form a.continuationiof the compressofifllet apass'age 25 and which are spaced"aparf byfahimiibe'rgbf vanes '37. 'The forward ends or 'thesleeYe's*3Warfd36 'l are fastenerl as by 'b'olts3'8 to'thei'riiigs'fwandqzfespec'tively. 'The'plates I6and strand the ringm and *sleeve 34 forman'enclosure forthefredutiongear.

For the propeller drive, the forward end ofthel .e'rld be'illZG-i'ssplined to a gear 40 -'conne'cted,ias b'y a"loose= *sp'line'd'ring'42-to a gear 44'jou'rnalled on the propller 7 shaft T2. The -gear"44, which "is supported againstraiial movement on the shaft I2, havingits'hub clamped between a shoulder "45 'arid'ablamping'ring'miforms {thesun gear of a planetary *reduction g'e'a'r"'asselfiblyllandjour'nall'e'd on t a projecting hub "50 "bnthe "sun' gear fl. Thepinions 47 are also in meshwith a ring gear- $2 haying-"on its outer"surface "helical "splines "engaging Patented May 29, 1956 meshes with aseries of-pinionsflTearrieii 'b'ya cage 48 e ring 20. The helicallysplined ring gear 52 forms a part of a torquemeter, hereinafterdescribed, the ring gear 52 being eflectively stationary within itshousing which consists of the plate 16,'the ring 20 andthe sleeve 34.

The cage 48 has splined thereon a gear 58 which forms the sun gear of asecond planetary reduction gear assem- .bly and is concentric to theaxis of the propeller shaft. T Gear 58 meshes with a series of pinions60 carried by a cage 62 which is splined to the propeller shaft. The.pinions 60 mesh with a ring gear 64 which has an integralflange 65clamped between the outer edge of plate 16 and the frame element 18 forholding the gear 64 in position. By this arrangement of gearing, thecompressor.

rotor speed is stepped down to a suitable propeller speed by means oftwo stages of planetary gearing as will be apparent, the reduction inspeed being accomplished in a small space.

' 'As above stated, the propeller shaft is drivenby the -which'extendsforwardly from the turbine section of the power plant through the burnersection as shown in Fig. 4 and throughthe high-pressure section of thecompressor as shown in Fig. 3. The forward end of the shaft 88 has'splined thereto the end bell 90 for the rotor of the low pressuresection 91 of the compressor, which is also,

- driven by the low pressure turbine stages.

-' Referring now to Fig. 3, the rotor of the low pressure section of thecompressor consists of a number of rotor discs 92, each having a row ofblades 94 on its periphery and each having rings of projecting tubularbosses 96 on opposite sides thereof which receive through bolts 98 zand'whichengage end to end for spacing the discs apart. The bosses 96 aretangential to an integral annular flange 299,- Fig. 8, which cooperateswith the adjoining flange ronithea'djacent disc to form a cylindricalsleeve extend- .ing .between adjacent discs. The end bell 26 at the up-;stream end of the low pressure rotor and the opposite end bell 90asshown, have outwardly extending flanges 101, and 102, respectively,which engage between the bosses 960i the outermost compressor discs andthe discs adjacent thereto thereby supporting the row of discs -,inproper relationwithin the power plant. The outer peripheries of theflanges 101 and 102 have rows of openings 103 to receive the throughbolts 98 and hold the endbells in proper relation to the discs. It maybe noted that by having the end bells located axially inwardly h of theoutermost CQInpressor discs the overall length of the rotor maybemateriallyshortened. Thesucces'sive rows of blades 94 on the compressordiscs alternate with rows of stationary vanes 104 which T are supportedand axially spaced by surrounding casing rings 106, the latter beingarranged in abutting relation T and. being secured'together as by bolts108 in building up the'com'p'ressor casing. The vanes 104 are mounted at"their outer ends on semi-annular plates 110, Fig. 6, each .platehavinga radially extending flange 112 fitting bej' tween the adjacent flanges114 and 116 on the casing 'r ings. It will be noted that each casingring 106 has a recess 118 therein to receive the vane carrying plates sothat when the vanes and the plates have been assembled w ithin thecasing rings, the inner wall of the casing, I which defines .the gaspath, is substantially smooth. "The inner-ends of the stator vanes 104in each row i are interconnected by a split ring 120, Fig. 7, to whichis Yalso. secured a sealing member 122 having spaced flanges 124extending radially inward and engaging with lateri ally projectingflanges 126 on the compressor discs, It

the discs to the end-bells 160 and 162.

. 4 will be noted that the flanges on opposite sides of each compressordisc are not necessarily in axial alignment since by selecting suitablediameters for the flanges 126, it is possible to control the area of thedisc that is exposed to the interstage gas pressure thereby makingpossible the control and balancing of the total end thrust on thecompressor section. The flanges 126 also serve to stiifen the discsagainst axial bending resulting from uneven pressure loading on thediscs.

The low pressure compressor rotor is supported at the inlet end by thebearing 30, above described, and at its downstream end by a bearing 128carried by a supporting web 130 extending inwardly from a ring 132 whichforms the inner wall of the annular gas path 134 between the lowpressure compressor sectionand the high pressure compressor section. Thering or sleeve 132 is supported within a substantially parallel outerring 136 by struts 138 which may be hollow for the purpose of supplyinglubricant to the bearing 128 and for scavenging the oil therefrom. Theouter sleeve 136 is connected to and forms a continuation of thecompressor casing. as will be apparent.

Referring now to Fig. 5, the second and third turbine stages which drivethe low pressure compressor section are supported by a bearing 140located downstream of the turbine discs. As shown, the last turbine'disc72 has an; annular flange 141 with a stub shaft 142 mounted thereon. Theouter end of the shaft 142 is supported by the bearing 140. The bearingis supported a spider 144, the outer periphery of which has a splineconnection 146 to a ring 148 supported within the annular exhaust duct150 for the turbine. The spline connection permits radial expansion ofthe supporting ring with reference to the spider.

The three spaced bearings 30, 128 and 140 support the low pressurecompressor rotor and its driving low pressure turbine section forrotation within the power plant independently of the remainder of therotating parts.

, Thatis to say, in the testing or assembly of the overall power plant,it is possible to assemble the low pressure compressor and turbinesections, above described, and run them within the supporting structurewithout the necessity for mounting the outer or high pressure spool,

. which consists of a compressor section and the first turbine stage,hereinafter described.

Referring now to Figs. 3 and 4, the outer spool includes 1 the highpressure compressor section, the rotor 152 of which is made up of anumber of separate discs 154 each having on its periphery a row ofblades 156. The compressor discs are assembled in the same manner as thecompressor discs of the low-pressure section, being held together by athrough bolt 158 which also secures The blades 156 of the several stagesalternate with rows of stationary vanes 164 which are secured in placein a manner similar to the vanes 104 of the low pressure section.Thecasing rings 166 of the high pressure section form a continuation ofthe low pressure casing and the sleeve 136 and define the outer wall ofthe gas path through the compressor. y

The upstream end of the rotor 152 is supported by a bearing 168 mountedwithin the same-supporting web 130 that carries the bearing 128. At thedownstream end of the compressor section, the rotor is supported by abearing 170 which is carried by a bearing housing 172. The housing isheld in position by radially extending struts 174 through whichaccessory drive shafts 176 extend, as will be later described. The outerends of the struts are integral with or positively connected tothediffuser element 178 which extends from the discharge end of thecompressor to the combustion chamber or chambers in twith cooperatingsplines 1188 on the endbell-- 162. A gear 190'is? also splined to the'shaft ISZ -adjacentEtO the 'bearing 170 for driving'accessories,as-willzbefpointed out.

-The' sleeve 182 surrounds the shaft 1 F88 and, 1 if desired,"athereim'ay i be Ia bearing r192rprovided between thesleeve iand'theishaft ata point'adjacent toxhe bearing 170. At its downstream end,the sleeve 182 :has a 'radially 'exiten'ding :flange 194, *Fig. 5, the:outer :rirn of-which is secured as by bolts 19610: a "flange 1198. 01:-the turbine lidisc. (Fhe outer rim of the' flange is connected to theirest 'of the flange 194 bya flexible cylindricaliportion 1 95.1The'--bearin'gs"168, 170 and 180 support the compressor erotor 52,the='firs't: turbine :disc, nndzthe connectingshaft "1'82 ".inrsuch -:ar manner :thatkthis'ipatt of the power ;plant 'zmay be' 'assenibled andtestedwithin rthe supporting structur'e without the :"necessity*forindorporating in the as- '1sembly the'low.:pressurec'ompressorwsectionflor'thesecond -iandlthirdsturbinestages.

' 'Fhe: combustion chambers in which fuel is-burned 'b'e-'rtweentthecompressor-and turbine: form the subject ma-tthat'atheditfuser element fls consistsof-an outer 1ing-200 and aniinnerx-rin gdw,the upstream ends; of which are held in spaced relation toeach other bystraightening -wanes 204. The outer rin'g 200:.hasa flange 206 by whichthe iiiifuser :is connected to the downstream Tend oi -theicor'npressor'xcasing. The rings200and-202 divergein the' dire'ction \of1 airflow: to -form: the diffuser passage and LthetsupPortingelement 184is connected to the downst ream zend of the inner ring 202. burnercasing-208 asurrounds: the :burners or cornbust-ion chambers 209 and ismonn'ected-lat: its upstream end to the downstream; end of Jth'ering-.200 rasaby bolts 210. gAlthough'the-casing @208 :1 may the a"single cylindrical element, it is shown here as made up of severalflanged segments held together as ebwbolts 212. I 1

Spaccd radiallyinward fromwthe casing-208-is a sleeve flli forming theinner walLof the-=-burnerduct,flth s wall 5 beingconnected at :its-upstrearn end to t the firing 202 wand rits downstream end-engagingwith asupporting t ring 218, wEiguzS, i'for the inner endsof-=the nozzlevanes .76' for {the rfirst "turbine stage. heat shield t220-.- 1inesthe; casing 2208*' and= another heat-shield 222 lines the sleeve-216,both I shields b'ein'g spaced from :the adjacent-part to spermit a -flow:of :cooling aintherethr'ough.

"TIlre casing -208-with-its heat shields 220 .is positioned 1- inspacedrelation-to the sleeve *216 and defines therebetween: anannular ipathforgas between "the compressor and'ttheaturbine. Within th-is -annularpatharelocated the rburner 5cans or cornbustion 'chambers 209 which, inthe arrangement shown, consist of concentric sleeves 224' and226;opemattheirupstream end to .receive .fuelirom .noz- :zles 228and-tconverging--atthe downstream end to :form :a :smaller annular-;disoh-argeopening -230 forathe gas as itcapproaches-theiturbine.

t *The turbine nozzles, 'g. 5, are supported from the"downstreamendofthe-casing 208 bya ring 2132 held at wone' -end as-"by-bolts 234,-to the casing208 and, at the "downstream end bolted to.the flangeconnection between "the -second andthirdstage turbine.nozzles, as Well be apsparent. The arrangement-of this ring,,which is-frusto- :conical in theconstructionqshown issuch that the turbinecasing can expand without being misaligned-with respect uto -rthe.compressor and burner cases. [Heat shields236 t .and 238 are located inspaced parallel relation, to the spacing lugs- 240 thereon so that airflowing; through the prevent overheating.

flcombus'tion chamber externally of thetsl'e'eve 224 may fi2w "throughholes 242 in' the heat :shieldmf220 enterthe space between theinnermost: shield i238 and tthe adjacent rshield 236. 5 Tile -attachmentof-1=ing 232 'to the turbine casing between the "secondand third stagenozzles {provides a -relatively coolrpoin t of attachment ascontrastedtothe temperatureof" the first stage nozzle. Moreover, the ring 132 ats asa" seal --between j'ihfi': casing "and the surrounding 10 -structure toni'aintain, in the *chamber surrounding the first and second 5 stagenozzle, the compressor discharge --pressu're=.so I that the :pressuresinside and outsidesof the nozzle rings are substantiallybalancediand-:the:first stage I nozzle. is not-subjected any unbalancedpressures-tendto burstthe nozzle-ring. ltwill-be further notedthat-the-flow of cooling-air-is fromthecoolouter-end of the ring-232-tothehot inner end, such thatthe -ring :may adjust itself byzthermalchanges-,to-the thermal expanision of thecasing.

inwardly extending flange 244 which at its innenend -is in alignmentwiththe downstrearn end-of the-heat shield2 20 thereby guidingtthe-flowof cooling air from around th-is shield fiIItO- thE-SPaC C betweenthe turbine "shields. Ihe

inner edge of. the flange 244 is axially spaced slightlyifirom ;-thewall MQ-fOrmingthe-outer wall of the turbine-inl et duct 248. Thisspacing defines amassage 250 through which cooling-air from theshieldsflowsfintothe inlet duct and travels along the inside surface of thewall 7246 to The inner-mostshieldz its, as above-stated'fisspacedrfromtthe adjacent 'i shield 23 6 so that cooling air fromihe combustionchamber hows between thefse two shields. This cooling air=discharging atthe open downstrearnends 101 :the shields is directed against theoutside :surfac'e of the turhine casing adjacentto the point ofattachmentbf "the: supporting ring 232. From thislpoint the cooling-air."flowsforwardly over-the casing rings 80 "78 and thence along the outersurface of the "wall"24'6 to enter -."1 o ,prevelit overheating of 'thebearings" I70 rand"i80, "Fig-. 4, cooling air fror'n' thecompressor:circiilates' through "the chamber enclosed by the inner51L202 6f The Elffuser and also inwardly ofthe-supporting"frusto-cohical4 rneniber'l18'4. -The meriiber'18'4"has' holes 'isl through which-"thecool air flows into the space 253 hetvv een4he combustion charnberwall'2'16 andthe-mein'her I84. downstream end of this spacemaybeclosedfby a fdiatp'hragm 254 which may have nozzles -256,"'Fig.' 5,rhdunted-t'hereonfor guiding'the 'air flowing through the cooling spacesagainst the first stage turbine disc adjacentits periphery. 'It maybe-nOted in connection with{the c661- "in g-air that the lastcompressordischas radially spaced "flanges 258 each "of whichis-engageahle hy sealing tile- 55 ments 260'carried'by the wall 202which controlibe amount df compressed air escaping atthistpoiiiffor use.in cooling. I I l p i Since the bearings 170 and '180 must belubricatdfthey "are-enclosed -withinthe support 172 arid the" mountingring I86 and bya sleeve 262 extendingbetweenfthe mounting ringandsupport. This sleeve '262fsurrounds the Yshafts'SS and 132 to deiineachamber 2'64 which enclo'ses the bearings ahd'interconnects them.The-chaniber-JZM I is closed at its forward end by a suitable sealzhfipapart ofwh'ichis carried bythe cover ..plate" 2'58."for theupstream end of this chamber. 'The'lower end of the chamberis closed .bya seal 270. 'The sleeve may-.havean oifsetf2 71 therein to allow'foraiiial expansion. 7 .Lubricant' is supplied fthrougha lubricant: inlet.pipel2i72 'locate'd in one of the vanes 174 and by-pa sswipes ff2i74and.276 leading -to the bearing. The chamber 264 is :scavenged -throughaduct 278 connected to-a scavenge pump, .not shown.

The space upstream of'the first'stage turbine disc lietween the disc andthe diaphragm- 254 is closed by t -he'seal 270 so that it becomesunnecessary to provide other seals 1 to control leakage of power fluidfrom the space between the first stage nozzle and the cooperating bladeson the first turbine disc. Between the first and second-discs,

however, it is necessary to prevent leakage around the i inner end ofthe diaphragm for the second stage nozzle. To this end the second stagenozzle 81 carried by casing ring 80 has an inwardly projecting diaphragm280 carryence to the radius of the first stage disc, it is possible todetermine the area of the first stage disc that is exposed to the highpressure at the inlet side of the second stagenozzle. Thus, the onlyarea of this disc exposed to the -high pressure at'this point is thedisc surface radially outward fromthe sealing flanges.

The remainder of the first stage disc is exposed to the lower pressureexisting at the downstream end of the second stage nozzle.

A similar sealing arrangement is provided between the second and thirdturbine stages by a diaphragm 285 on the inner periphery of the thirdstage nozzle 83. In this -way, by selecting the area of the discsexposed to the high pressure, it is possible to control the amount ofaxial thrust exerted on the turbine rotor assemblies by the pressuresexisting in the turbine.

Lubrication for the bearing 140 is provided by a lubricant pipe 286extending through a radially extending shielding tube 288 to a housing290 surrounding the bearing 140. The housing is in two parts, thedownstream part 291 being cup shaped and attached to the plate 144.

v The other part 292 is on the upstream side of plate 144 I and at itsupper end carries a seal 293 surrounding the shaft 142 to preventoilleakage. Oil is scavenged from this housing through the tube 288. Asecond housing 294 surrounds housing 290 and is similarly shaped, its

open upstream end being close to the upstream endof the windage cover304 over the ends of the holding bolts 196 and similar windage covers305 may be fitted over the ends of the clamping bolts 98 and 158 for thecompressor sections. Each of these covers is in the form of a hollowannulus 306, Fig. 10, which covers the bolt ends and the clamping nutsthereon. In the case of the compressor covers the edges of the annulusfit between spaced flanges 307 and 308 on the endmost compressor disc.The covers are held in place by screws 310 fitting I in the ends of thethrough bolts.

The power plant may be started by starting the outer spool with theinner or low pressure spool allowed to windmill as a result of the flowof gas through the unit. For the purpose of starting the outer spool, amotor 312 may be carried by an accessory bracket 314 in which isjournalled a shaft 316. The motor shaft 318 engages splines in one endof the shaft 316 which carries a gear 320 meshing with a gear 322 on oneof the accessory drive shafts 176 (Fig. 4). With this startingarrangement the starting motor is required to spin only the outer spooland accordingly much less starting power is required than would be thecase if the entire unit were driven by the starter. It has been foundthat, in a unit of the type described, the outer spool will operate byitself when the inner or low pressure spool is either stationary orwindmilling.

In certain instances, as forexample if the aircraft is on the ground oron a carrier deck, it may be advantageous to prevent windmilling of thepropeller while the engine is idling. To accomplish this, the innerspool "may have a brake applied thereto, as best shown in Fig.

It will be 8 11. As shown'in Figs; 2 and 11, certain of the accessoriesare driven from the inner spoolwhich carries a driving gear 324 inmeshwith a series of gears 326 on radially extending drive shafts 328extending through the hollow vanes 37. One ofthese accessories shaftsmay drive the scavenge and oil pressure pumps 330, Fig. 2, and anothershaft maybe arranged to drive other accessories through similar gearingshown at the top of Fig. 2.

As shown in Fig. 11, another one of the radially extendingdrivingshafts328 carries at its outer end a brake drum 332 in a housing 334mounted on the outer sleeve 36 of the compressor inlet. This housing hasa cap 336 which supports a series of brake shoes 338 normally held,

as by a spring 340, out of contact with the brake drum and moved intocontact with the drum by means of an inflatable tube 342 Fluid forexpanding the tube is admitted through a duct 344 from a suitablesource, the supply being controlled as by manual valve 346. Thus withthe power plant stopped the brake may be energized to hold the innerspool from rotating while the power plant is being started, or when thepower plant is idling the propeller may be'feathered and the brakeapplied for the purpose of stopping the rotation of the inner spool. Ina multiengine installation the brake may also be advantageous forpreventing windmilling of the propeller in the event that the powerplant is stopped in flight.

It is tobe understood that the invention is not limited to the specificembodiment herein illustrated and described, but may be used in otherways without departure from its spirit as defined by the followingclaims.

I claim:' 9

1. In a gas turbine power plant, a multistage compressorfhaving at leasttwo independently rotatable high and low pressure rotors, a multistageturbine having at least two independently rotatable rotors, one turbinerotor being connected to each compressor rotor, a supporting frame forthe power plant, bearings carried by said supporting frame forseparately and independently supporting each compressor rotor atopposite ends and its associated turbine at one side thereof, andmounting means for said bearings extending between the supporting frameand the bearings.

2. In a gas turbine power plant, a multistage compressor having twoindependently rotatable high and low pressure rotors in axial alignment,a multistage turbine having two independently rotatable high and lowpressure rotors, the high pressure compressor and turbine rotors beingconnected together to form a rotatable unit and the low pressurecompressorand turbine rotors being connected together to'form aseparately rotating unit, a supporting frame for the power-plantincluding'the compressor casing, and at least three spaced bearingscarried by the supporting frame for supporting the high pressure turbineand compressor rotor unit within the supporting frame and three otherspaced bearings carried by the supporting frame for supporting the othercompressor and turbine rotor unit independently of the high pressurerotor unit.

3. Ina gas turbine power plant, a multistage compressor having twoindependently rotatable high and low pressure rotors in axial alignment,each rotor having a number of rows of blades thereon, a multistageturbine having two independently rotatable high and low pressure rotors,the high pressure compressor and turbine rotors being connected togetherto form a rotatable spool, the low pressure compressor and turbinerotors being also connected together to form a second spool, the firstspool surrounding the second spool and being concentric therewith, asupporting frame for the power plant, said supporting frame having rowsof stator vanes therein alternating with the rows of blades on each ofthe rotors, bearings carried by said frame for supporting the highpressure spool and other bearings carried by said supporting frame forseparately supporting the other spool, one bearing for the high pressurespool being positioned adjacent to and airman? and iloWnstream-ofthelow-prssnfe turbine rtbr;

. In-" gas-turbine-powerplantfyii itiltistagecompresoindependentlyirotfitable high andlowf'pressure rotorsunaxial-alignment,-amultistage turbine having ng -for the-lowpressurespoole locatefdailjacent 1 pressure compressor rotor and the upstream side ofthe high pressure turbine rotor and otherbearings, also carried by thesupporting frame, for supporting the other spool at theupstream'and"downstream ends of the low pressure compressor rotor and on thedownstreamside of the turbine rotor. g

5. In a gas turbine power plant, a multistage compressorhaving at leasttwo independently rotatable high and low pressure rotors each havingrows of blades thereon, a casing surrounding said rotors and having rowsof 'stator vanes therein cooperating with the blades on said rotors, adiffuser section having inner and outer walls diverging in a downstreamdirection and located on the downstream end of said casing and intowhich air from the compressor is discharged, said walls being connecteda to said casing, a combustor at the downstream end of the diffuser andhaving a peripheral shell connected to the diffuser, a multistageturbine at the downstream end of the combustor, said turbine having atleast two independently rotatable high and low pressure rotors eachhaving at least one row of blades thereon, a turbine casing surroundingsaid turbine rotor and having rows of stator vanes therein cooperatingwith the blades on said' rotors, veach turbine rotor being connected toa corresponding compressor rotor to form independently rotating spools,said compressor casing, difiuser, combustor shell and turbine casingbeing connected together and forming at least a part of a supportingframe for the power plant,bearings carried by said supporting frame forseparately and individually supporting each compressor rotor with itsassociated turbine rotor, and mounting means for said bearings extendingbetween the supporting frame and the bearings, said mounting meansincluding a frusto-conical support connected to the inner wall of thediffuser and extending towardvthe turbine, the turbine end of thesupport carrying one of the bearings adjacent to the turbine.

6'. In a gas turbine power plant, a multistage compressor having atleast two independently rotatable high and low pressure rotors eachhaving rows of blades thereon, a casing surrounding said rotors andhaving rows of stator vanes therein cooperating with, the blades on saidrotors, a diffuser section having inner and outer walls diverging in adownstream direction and located on the downstream end of said casingand into which air from the compressor is discharged, said walls' beingconnected to said casrienziingmetweeniitneisnpporrtng: rrarne anduhebearings, i

said mounting means includingia frusto conical' support connected to theinner wall of the diffuser and extending toward rtheimrbine,ithetunbineaendiofrthewsiipport carrying one'of thebearings adjacentato theturbine. In a,gas turbine power plant, a multistage compresfsorhavingtwoindependently rotatablefl high and lowptesfsure "rotors: inaxial'alignment,"each rotor havin'g'rowsof f hlades tlieronracasingsurroundingsaid rotor and having "fows ofstatorvanes"therein'cooperating withtheli blades "o'nj-said r'otors, adiffuser'section having innefrand' outerwallstdiverging-in"adownstreamfiir often and ocatedpn the dowfistreamenmof -said casing' and intowliich air from the compressor isdischarged, said walls being connected to said casing, a combustor atthe downstream end of the diffuser and having a peripheral shellconnected to the diffuser, a multistage turbine at the downstream end ofthe combustor, said turbine having two independently,

rotatable high and low pressure rotors in axialalignment, each rotorhaving at least one row of blades thereon, a

turbine casing surrounding said turbine rotor and having I surroundingthe second spool and being concentric therewith, said compressor casing,diffuser, combustor shell and turbine casing being connected together toform at least a part of a supporting frame for the power plant, bearingscarried by the supporting frame for supporting the high pressure spoolat the upstream and downstream ends-of the high pressure compressorrotor, and at the upstream side of the high pressure turbine rotor, andother bearings also carried by the supporting frame for supportingtheother spool at the upstream and downstream ends of the low pressurecompressor rotor and on the downstream side of the turbine rotor.

8. In a gas turbine power plant, a multistage compressor having twoindependently rotatable high and low pressure rotors in axial alignment,each rotor having rows of blades thereon, a casing surrounding saidrotor and having rows of stator'vanes therein cooperating with theblades on said rotors, a diffuser section having inner and outer wallsdiverging in a downstream direction and located on the downstream end ofsaid casing and into which air from the compressor is discharged, saidwalls being connected to said casing, a combustor at the down stream endof the diffuser and having a peripheral shell connected to the diffuser,a multistage turbine at the downstream end of the combustor, saidturbine having two independently rotatable high and low pressure rotorsin axial alignment, each rotor having at least one row of ing, acombustor at the downstream end, of the diffuser and 7 having aperipheral shell connected to the diffuser, a multistage turbine at thedownstream end of the combustor, said turbine having at leasttwoindependently rotatable high and low pressure rotors each having atleast one row of blades thereon, a turbine casing surrounding saidturbine rotor and having rows of stator vanes therein cooperating withthe blades on said rotors,each turbine rotor being blades thereon, aturbine casing surrounding said turbine rotor and having rows of statorvanes therein cooperating with the blades onsaid rotors, the highpressure compressor and turbine rotors being connected together to forma rotatable spool, the low pressure compressor and turbine rotors beingalso connected together to form a second spool, the first spoolsurrounding the second spool and being concentric therewith, saidcompressor casing, diffuser, combustor shell and turbine casing beingconnected together to form at least a part of a supporting frame for thepower plant, bearings carried by the supporting frame for supporting thehigh pressure spool at the upstream and downstream ends of the highpressure compressor rotor, and at the upstream side of the high pressureturbine rotor, and other bearings also carried by the supporting framefor supporting the other spool at the upstream and downstream ends ofthe low pressure compressor rotor and on the downstream side of theturbine rotor, the bearing on the upstream side of the high pressureturbine rotor being supported by a frusto-conical support connected tothe inner wall of the diffuser and extending toward the turbine with thebearing mountedat the turbine end ,of the support. :1 L,

Ref erencesCited in the file of UNITED 'STATES PATENTS 1 Anxionnaz eta1. Feb. 21,1950 Lysholm Apr. 22, 1941 Trailpel May 11, 1943 ForsythJuly 1, 1947 Cameron Jilly 12, 1949 Notestein et ,1 Nov. 1, 1949 JudsonNov. 22, 1949 FOREIGN PATENTS

